research bits

Daniel Maler

Congratulations to Daniel Maler who won the IEEE Nuclear and Plasma Sciences Society (NPSS) 2022 outstanding student paper award, presented at the International Conference on Plasma Science (ICOPS), Seattle, Washington, USA, 22-26 May 2022. Daniel was awarded for the paper “Peculiarities of planar shockwave interaction with air–water interface and solid target" published in the journal “Physics of Plasma” along with Sergey Efimov, Yakov Krasik and collaborators from Sweden, United Kingdom and France. The paper was also chosen as Editor’s pick and displayed on the journal's homepage.

In their paper the researchers used the imaging capabilities of the European Synchrotron Radiation Facility (ESRF) to explore the evolving dynamics of underwater electrical explosion. In experiments a wire array, having planar symmetry, comprised of thin copper wires, was submerged underwater. Above the array the researchers either placed an aluminum target or presented an air-water interface. Using a pulse generator, a high current pulse reaching ~30 kA was delivered within 1 μs to the array, inducing rapid phase transitions (solid – liquid – vapor - low ionized plasma) of the wire material, leading to an explosion. As the wire exploded, strong shockwaves were generated, interacting with either a solid target or an air-water interface. Using radiography imaging, the internal structure of the wires was revealed, together with the waterflow behind the generated shockwaves.

These experiments revealed several phenomena such as wire additional acceleration without depositing energy into the system, cavitation of the water resulting in negative pressure and hydrodynamic instabilities at the air-water interface behind the shockwave propagating in air. A two-dimensional hydrodynamic simulation was used to explain much of the dynamics in the system. This method of imaging exploding wires has also offered the opportunity to estimate many plasma parameters such as electron density, coupling coefficient and the conductivity of the plasma, demonstrating the transition of the plasma from a weakly ionized to strongly ionized following rapid energy input and, in turn, wire explosion.

Daniel also won the prestigious NPSS Barker Graduate Student award on April 2022.

Great job Daniel!